If something like this happens, they need to do something right away, somehow the rotor continues to rotate even with 2 blades. This results in a massive imbalance. The wind turbine will either crash on one side or the other, depending. If this happens to any wind turbines out there, they need to stop it spinning right away and replace the blade afterwards.
From what it appears, somehow a blade snapped off the rotor, and the rotor continued to spin with two blades and a stub where the third should have been. The resulting imbalance of the rotor caused by the missing blade caused the tower to sway dangerously, weakening and then breaking the frame structure resulting in the windmill falling over.
It's a wonder how that windmill even spun at all with a missing blade. I would imagine, unless the blade broke off that same day, any slowdown in the winds and the remaining blades would just swing slightly back and forth and wouldn't spin.
If the wind generator was supplying the electrical grid it would be spinning in synchronism with grid frequency, i.e. electrically coupled to the system. If this wind machine remained coupled to the grid after losing a blade it could keep rotating at a constant speed because it's now being "motored" by the grid. It has become a load on the system, consuming electric power like a motor would.
makes me so sad to see the tiny houses inbetween the turbines and thinking about the people who has to live there... the world has gone absolutely crazy.